Re: [PATCH v3 03/23] iommufd/viommu: Allow driver-specific user data for a vIOMMU object

Vasant Hegde
2025-05-06T11:05:51Z

On 5/2/2025 4:31 AM, Nicolin Chen wrote:
> The new type of vIOMMU for tegra241-cmdqv driver needs a driver-specific
> user data. So, add data_len/uptr to the iommu_viommu_alloc uAPI and pass
> it in via the viommu_alloc iommu op.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant

>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
> Acked-by: Pranjal Shrivastava <praan@google.com>
> Acked-by: Alok Tiwari <alok.a.tiwari@oracle.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
> include/uapi/linux/iommufd.h | 6 ++++++
> drivers/iommu/iommufd/viommu.c | 8 +++++++-
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
> index f29b6c44655e..cc90299a08d9 100644
> --- a/include/uapi/linux/iommufd.h
> +++ b/include/uapi/linux/iommufd.h
> @@ -965,6 +965,9 @@ enum iommu_viommu_type {
> * @dev_id: The device's physical IOMMU will be used to back the virtual IOMMU
> * @hwpt_id: ID of a nesting parent HWPT to associate to
> * @out_viommu_id: Output virtual IOMMU ID for the allocated object
> + * @data_len: Length of the type specific data
> + * @__reserved: Must be 0
> + * @data_uptr: User pointer to an array of driver-specific virtual IOMMU data
> *
> * Allocate a virtual IOMMU object, representing the underlying physical IOMMU's
> * virtualization support that is a security-isolated slice of the real IOMMU HW
> @@ -985,6 +988,9 @@ struct iommu_viommu_alloc {
> __u32 dev_id;
> __u32 hwpt_id;
> __u32 out_viommu_id;
> + __u32 data_len;
> + __u32 __reserved;
> + __aligned_u64 data_uptr;
> };
> #define IOMMU_VIOMMU_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VIOMMU_ALLOC)
>
> diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
> index fffa57063c60..a65153458a26 100644
> --- a/drivers/iommu/iommufd/viommu.c
> +++ b/drivers/iommu/iommufd/viommu.c
> @@ -17,6 +17,11 @@ void iommufd_viommu_destroy(struct iommufd_object *obj)
> int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
> {
> struct iommu_viommu_alloc *cmd = ucmd->cmd;
> + const struct iommu_user_data user_data = {
> + .type = cmd->type,
> + .uptr = u64_to_user_ptr(cmd->data_uptr),
> + .len = cmd->data_len,
> + };
> struct iommufd_hwpt_paging *hwpt_paging;
> struct iommufd_viommu *viommu;
> struct iommufd_device *idev;
> @@ -48,7 +53,8 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd)
> }
>
> viommu = ops->viommu_alloc(idev->dev, hwpt_paging->common.domain,
> - ucmd->ictx, cmd->type, NULL);
> + ucmd->ictx, cmd->type,
> + user_data.len ? &user_data : NULL);
> if (IS_ERR(viommu)) {
> rc = PTR_ERR(viommu);
> goto out_put_hwpt;